Coaxial cable selector switch



Mardi l, 1955 M. w. sAwYER ET A1. l 2,703,346

COAXIAL CABLE SELECTOR SWITCH grroie/vf/ March 1, 1955 M. w. SAWYER ET AL.

COAXIAL CABLE` SELECTOR SWITCH 2 Sheets-Shee 2 Filed Aug. s, 1951 COAXIAL CABLE SELECTOR SWITCH Marshall W. Sawyer and Reginald G. Kenway, Los Angeles, Calif., assignors to Transco Products, Inc., Los Angeles, Calif., a corporation of California Application August 3, 1951, Serial No. 240,252

4 Claims. (Cl. 200-4) Our invention relates to new switch means for connecting a coaxial cable selectively to one or more other coaxial cables or coaxial conductors.

it is an object of the invention to provide a coaxial switch which is of relatively simple form, but has a number of important advantages. An important advantage of the invention is that it has a low voltage standing wave ratio in a line of specified impedance as a function of the diameters and lengths of all R. F. conducting surfaces. A further advantage is that the attenuation between unused connectors is high because of the placement of connectors on the front plate and front plate connector assembly physical relationship to the rotor body. For example, the characteristic loss of the switch when inserted in a matched 50 ohm transmission line is less than 1/10 of l db greater than an equivalent length of teflon insulated transmission line at the frequency of 10,700 mc. and is negligible at the lower frequencies. Our coaxial switch is especially useful in radar. In one application thereof it has a voltage standing wave ratio of less than 1.5-1 when inserted in a transmission line having a characteristic impedance in the order of 50 ohms in the spectrum between D. C. and 10,700 mc. Furthermore, in this coaxial switch the form and cooperative relation of the parts are such that its useful life is about 100,000 cycles of operation.

lt is an object of the invention to provide a coaxial switch wherein a low Voltage standing wave ratio is obtained as a result of an arrangement of parts and the critical ratios of R. F. conducting surfaces, including means Vfor carrying inner and outer electrical conduction paths through the switch and disposing certain of the contact faces of the switch in a relation such that small measures of disalignment of parts wi-ll not aiect the voltage standing wave characteristics of the switch.

lt is a further object 'of the invention to provide a coaxial switch having a central receptacle and the plurality of other receptacles arranged at a circle around the central receptacle, with a rotor adapted for movement so as to provide selective communica-tion between the central receptacle and any one of the other receptacles, bearing means for controlling the movement of the rotor so that contact forms characteristic of the invention may be employed, thereby contributing to the important advantages which the invention has.

it is a further object of the invention to provide a coaxial switch wherein the parts are so related that the minimum of close tolerances need be preserved accordingly, variations of dimension throughout various parts of the switch will have no eirect whatsoever on the voltage standing wave ratio.

Further objects and advantages of the invention will be brought out in the following specification where we have described a preferred embodiment of the invention in detail for the purpose of completeness of disclosure, it being intended that the explanation of these details shall not limit the scope of the invention set forth in the appended claims.

Referring to the drawings which are for illustrative purposes only:

Fig. 1 is a cross-sectional view of the coaxial switch;

Fig. 2 is a section taken substantially as indicated by the line 2-2 of Fig. l;

Fig. 3 is a view of one of the cooperating body parts of the rotor of the invention;

Fi 4 is a perspective view of the curved insulator bead which is supported by the rotor;

nited tates Patent O "ice Fig. 5 is a perspective View of the curved conductor which is supported by the bead;

Fig. 6 is enlarged sectional view of one of the coaxial conductors; and

Fig. 7 is a perspective view of a swivel connector part.

Fig. 8 is a face view taken from the posi-tion indicated by the line 8-8 of Fig. 6.

A support l0 is provided which includes a cylindric wall 11 having a front 12 extending therefrom and front and rear plates 15 and 14 which are secured to the ends of the cylindrical wall 11. The front plate 13 supports the central receptacle 1S disposed substantially on the axis of the cylindrical wall 11, and an outer receptacle 16, in selected number, arranged upon a circle around the axis of the central receptacle 15. The coaxial switch disclosed in Fig. 1 has the outer receptacle 16 in triplicate and at an angular distance of The number of outer receptacles may be varied to suit the requirements of the user.

The central receptacle comprises a tubular metal wall 17 having an externally threaded outer end 18 for connection to the chief or outer conductor of a coaxial cable by means of fittings (not shown) now used in the art for connection of coaxial cables. The inner end of the tubular wall 17 is threaded into a metal bushing 19 which is retained in a shouldered opening 20 in the plate 13 by a nut 21, shim means 22 being employed between the annular shoulders of the plate 13 and of the bushing 19 for axial adjustment of the bushing 19 and the parts supported thereby. in the inner face of the bushing 19 there is a shallow annular recess which receives a perforated plate 23 which carries a ball projection 24 for the purposes of this disclosure, the inner annular portion of the disc 23 may be regarded as a continuation of the inner end of the tubular wall 17.

A cylindrical body of insulating material 25 is supported centrally within the tubular wall 17 and has therein an opening 26 through which the shank or pin portion 27 of axial conductor means Z3 extends. The pin portion 27 has a slender tubular socket 29 formed integrally with its leftward end, and a forked tubular connector part 30 is pinned on the record end of the pin portion 27 so as to complete the axial conductor means 28 by providing for connection with the inner conductor of the coaxial cable. The connector part 30 consists of a tube of resilient metal, such as beryllium copper. This tube has slots 31 cut therein, and the fingers 32, left between the slots 31 are deilected inwardly towards each other as shown.

Each outer receptacle 16 comprises a metal tubular wall 33 forming an outer conductor for connection to the chief or outer conductor or" a coaxial cable which is connected to the externally threaded outer end 34. A cy lindrical insulator 35 supports an axial conductor means 36 within the tubular wall 33. As shown in Fig. 6 the axial conductor 36 comprises a tubular shell 37, a resiliently supported Contact member 38 and a connector 39. The tubular shell 37 has a shank portion 40 which is a press tit in the opening 4l of the insulator 35. On the inner or leftward end of the shank 40 there is a head 42 having therein a cylindrical recess 43. An opening 44 of circular crosssection extends into the shank 40 from the bottom of the recess 43, the inner end of this opening 44 terminating at a wall 45. The contact member 38 has a cylindric head 45 which is received by the recess 43 of the head 42. A stem 46 extends from the head 45 into the opening 44. This stem 46 has a wide circumferential channel 47 therein arranged to receive indented portions 48 of the wall of the shank 40, the contact member 38 being thereby held in the tubular shell 37 but being permitted a limited axial movement. A coil spring 49 disposed between the end wall 45 and the inner end of the stem 46, urges the contact member 38 outwardly. The cylindric wall 50 of the head 42 has slots 51 therein to form a plurality of spring contact fingers 52 which are bent inwardly so that they continuously engage the cylindrical surface of the contact head 45. rl' he front face of the contact head 45 has a layer 53 of silver thereon, the face of which is tinished so as to conform as closely as possible to a plane perpendicular to the axis of the contact member 38. On the end of the shank 40 opposite from the head 42 there is an extension 54 of reduced diameter which receives the cylindrical end of the connector 39. This connector 39 like the connector 30, is slotted and has converging lingers 56 for connection to the inner conductor of the coaxial cable which is connected to the outer end of the receptacle 16.

As shown in Fig. l, the receptacle 16 is screwed into an opening 57 in the front plate 13. The axial conductor means 36 is so positioned in the tubular Wall 33 that the head 42 projects within an opening 58 of reduced diameter in the plate 13, which is a continuation of the opening 57 and is defined by an annular wall 59 which is a continuation of the tubular wall 33 of the receptable 16, with the contact face of the contact member 38 positioned so that it may be urged by the spring 39 to a posi tion where it will project slightly from the face 60 of the plate 13.

The rear plate 14 of the support 10 carries a bearing 61 which is axially aligned with the central receptacle 15.

A shaft 62 rotatably supported by the bearing 61 projects into the interior or" the support 10 and in turn supports a rotor 63. The rotor 63 is of divided form and includes a pair of symmetrical metal rotor body parts 64 and 65 having planar faces 66 which engage when the body parts are secured together by machine screws 67. Each body part 64 and 65 has therein a channel which extends through a half circle from a position adjacent the inner end of the centrol receptacle 15 to a position adjacent the inner end of the receptacle 16. Each of these channels 68 is of semi-circular cross-section so that when the body parts 64 and 65 are placed in face to face relation, these channels 68 will define within the rotor 63 a curved opening of circular cross-section which receives a semi-circular bead 69 arranged to support a curved conductor 70 adapted to connect the axial conductor means 28 of the central receptacle 15 with the axial conductor means 36 of an outer receptacle 16.

As shown in Fig. 4, the bead 69 comprises a pair of symmetrical cooperating bead members 71, each of which is semi-circular cross-section and has therein a channel 72 which receives half of the curved conductor 70. As shown in Fig. 5, the curved conductor has its inner end 73 a cylindrical head 74 from which a split pin 75 of resilient metal projects. As shown in Fig. l, this pin 75 projects along the axis of the receptacle 15 and into the slender tubular socket 29 of the axial conductor means 28, cooperating with the socket 29 to form a swivel electrical connection between the axial conductor 28 and the inner end of the curved conductor 70. On the outer end 76 of the curved conductor 70 there is a head 77 having a flat, circular front face 78 for engagement with the face of the contact member 38. The face 78 is accurately formed so as to lie in a plane conversely of the axis of the receptacle 16, such plane being the transverse glaneS defined by the contact face of the contact mem- The metal wall of the body parts 64 and 65 definingT the curved channels 68 defines an opening 68" of circular cross-section which not only receives the curved bead 69 of insulated material, but also defines an outer conductor for cooperation with the curved conductor 70 to propagate the wave transmission from the central receptacle 15 to an outer receptacle 16. An annular fitting 80 of resilient metal such as beryllium copper provides a swivel electrical connection between the either end of the rotor wall defining the opening 68' and the inner end of the tubular wall 17 of the central receptacle.

The fitting 80 comprises a cylindric wall 81 with slots so] that spring contacts 83 are formed, as shown in tg. 84 in the circular plate 23 and engage the wall of the plate 23 defining the opening 84. The fitting 80 has a flange 85 whereby it is secured to the rotor 63. As shown in Fig. l an annular index plate 86 is fixed on the face of the rotor 63 in a position concentric to the axis of rotation of the rotor 63. The index plate 86 is seated in an annular channel 87 in the face of the rotor 63 formed by semi-circular channels 87a and 87h in the rotor body parts 64 65. As further shown in Fig. l, the internal diameter of the fitting 80 is slightly smaller than thc external diameter of the bead 69 so that the inner portion of the fitting fill serves as a means for holding the bead 69 in the opening 63. An inwardly extending lip 88 on the index plate 86, projects over the fiange 85 and thereby secures the fitting Sii in operative position, The index These spring contacts 83 extend into an opening plate 86 has therein a number of openings or recesses 89, corresponding to the number of outer receptacles 16. In the present coaxial switch there are three recesses 89 dis posed at angular distances of 120 and being positioned so that the ball projection may extend thereinto as shown in Fig. l.

The plate 90 is secured to the outer end of the rotor 63 by countersunk screws 91, this plate 90 having therein an opening 92 of a diameter slightly smaller than the external diameter of the bead 69, so that the plate 90 serves as a means for retaining the bead 69 in the opening 68. A further purpose of the plate 90 is to make face to face electrical contact with the annular wall 69, 59 which defines the opening 58. The outer face 93 of the plate 90 is ground after it is secured to the rotor 63 so that this face 93 will closely correspond to the plane of the face 60 which is perpendicular to the axis of rotation of the rotor 63.

T he rotor 63 is secured to the shaft 62 as shown in Fig. l, by use of a plate 95 which is fixed in an annular recess 96 in the leftward face of the rotor 63. Means are provided for continuously urging the rotor 63 toward the front plate 13 of the support 10 so that at prescribed times there will be pressural contact between the faces 60 and 93. This means consists of compression springs 97 carried in recesses 98 in the rotor 63 and bearing against a reaction plate 99 which surrounds the rightward portion of the shaft 62 and bears against the rightward end of the bearing 61. This plate 99 is caused to rotate with the rotor 63 by an interengagement consisting of pins 100 which project from the plate 99 into openings 101 in the plate 95 and the rotor 63. A lever 102 is fixed on the outer end of the shaft 62, by Which rotation may be imparted to the shaft 62 so as to accomplish turning of the rotor 63 within the support 10.

When the shaft 62 is rotated, the ball projection 24 acts in cooperation with the index plate 86 to move the rotor 6f-3 leftward and lift the plate 90 away from the annular wall 59 when the outer end of the rotor ywall is dis aligned from the inner end of the receptacle 16. Referring to Fig. l, it will be noted that there is a small clearance between the shoulder of the wall which defines the opening 89 and the adjacent surface of the ball projection 24. Therefore, the rotor may be rotated through a small angle before the shoulder 105 engages the surface of the ball projection and starts to ride leftwardly over the surface of the ball projection 24. As soon as the shoulder 105 engages the surface of the ball projection 24, and rotation of the rotor 63 is continued, the sloping external surface of the ball projection 24 will force the rotor 63 leftwardly so as to separate the faces 60 and 93. Likewise, as the rotation of rotor 63 causes the outer end .of the rotor wall to approach the inner end of a receptacle 16, the play between the shoulder 105 of an opening 89 and the ball projection 24 will permit the wall or plate 90 to move into engagement with the annular wall 59 slightly prior to the time the head 77 at the outer end of the curved conductor 70 comes into true axial alignment with the contact member 38, producing a short widening engagement of the faces 60 and 93 and also a short widening engagement of the faces of the contact members 77 and 38.

The springs 97 hold the outer contact surfaces 93 and 60 together, and the spring 49 forces the contact member 38 into engagement with the contact part 77 of the inner curved conductor 7-0. As the surface of the ball projection 24 causes leftward movement of the rotor 63, as a result of rotation of the rotor 63, the spring 49 will cause the contact member 38 to project a short distance from the head 42 of .the axial conductor means 36. However, the plate 90 will not engage the left-wardly projecting contact member 38 for the reason that prior to the time the annular portion of the plate 90 is brought into overlapping relation to the contact member 38, the action of the bal-l projection 24 on the index platte 86 will have produced a separation of the surfaces 93 and 60 greater than the distance which the contact member 38 projects from the plane defined by the surface 60. In order to minimize detiecting forces on the body of the rotor 63 and the shaft 62 when the rotor 63 is positioned as shown in Fig. l, shims 106 are placed between the index plate 86 and the ball retainer plate 23, around the litting 80.

At certain places in the switch air insulation is provided between the inner and outer conductor means. For example, air is the insulation occupying the space within the openings 58 and 92 around the inner conductor parts 42 and 77. Also there is an air space around a portion of the connector part 39. The outer walls of these air spaces are reduced slightly in diameter as compared to the diameters of adjacent solid insulator parts. For example, the diameter of the opening 92 in the plate 9i), and of the opening 58, is slightly less than the external diameter of the bead 69 and of the cylindric insulator 3'5. In this way the impedance of the air insulation is adjusted with relation to the impedance of the solid insulation plants employed in the device. Similarly the air faces around the parts 74, 29 and 30 are of reduced diameter relative to the adjacent solid insulator parts.

We claim:

l. In a coaxial switch: a support having lthereon a central receptacle and outer receptacles, each of said receptacles having a tubular wall forming an outer conductor and an axial conductor supported within said tubular wall; a rotor supported tor rotation on :the axis of said central receptacle, said rotor comprising a pair of substantial-ly symmetrical body parts secured together with their contacting suraces dening a plane of separation, and with symmetrical curved channels of semi-circular cross section dening in said rotor a curved opening leading from the inner end of said central receptacle to the inner end of each of said outer receptacles; contact means arranged to make electrical connection of the inner end of said rotor wall ywith the inner end of said tubular wall of said central receptacle; contact means arranged to make electrical connection of the outer end of said rotor wall with the inner end of the tubular wall of each outer receptacle; an inner curved conductor in said curved opening of said rotor wall; insulator means for holding said curved conductor axially in said curved opening, said insulator means comprising a pair of insulator memibers of semi-circular cross section and being curved to t into said curved opening, and said insulator members having complementary grooves in the abutting faces thereof to receive said curved conductor; means electrically connecting the inner end of said curved conductor with the inner end ot the axial conductor of said central receptacle; and means adapted to electrically connect the outer end of said curved conductor with the inner end of the axial conductor of each outer receptacle.

2. In a coaxial switch: a support having thereon a central receptacle and outer receptacles, each of said receptacles having a tubular wall forming an outer conductor and an axial conductor supported within said tubular wall, the inner conductor of each of said outer receptacles comprising a tubular shell supported by insulator means, a contact pin axially movable in said shell and having a contact head arranged to project from the inner end of said sleeve, cooperative shoulder means on said sleeve and said pin to limit the movement of said pin, and spring means acting between said pin and said sleeve; a rotor supported for rotation on the axis of said central receptacle, said rotor having a wall dening a curved opening leading from the inner end of said central receptacle tc the inner end of each outer receptacle; Contact means arranged to make electrical connection of the inner end of said rotor wall with the inner end of said tubular wall of said central receptacle; contact means arranged to make electrical connection of the outer end face of said rotor wall with the inner end of the tubular wall of each outer receptacle; an inner curved conductor supported in said curved opening of said rotor Wall, the outer end of said curved conductor being arranged to engage said contact head of said contact pin of each outer receptacle; means electrically connecting the inner end of said curved conductor with the inner end of the axial conductor of said central receptacle; means for rotating said rotor on said axis so as to move the outer end of said tubular wall from one to another of said outer receptacles; and cam means arranged to bodily move said rotor so that its outer end will be spaced perpendicularly from the inner end of the tubular wall of each of said outer receptacles and pass across the exposed portion of said pin of each outer receptacle.

3. In a coaxial switch: a support having thereon a central receptacle and outer receptacles, each of said receptacles having a tubular wall forming an outer conductor and an axial conductor supported within said tubular wall, the inner conductor ofy each of said outer receptacles comprising a tubular shell supported by insulator means, a contact pin axially movable in said shell and having a contact head arranged to project from the inner end of said sleeve, cooperative shoulder means on said sleeve and said pin to limit the movement of said pin, and spring means acting between said pin and said sleeve; a rotor supported for rotation on the axis of said central receptacle, said rotor having a wall defining a curved opening leading from the inner end of said central receptacle to the inner end of each outer receptacle; Contact means arranged to make electrical connection of the inner end of said rotor wall with the inner end of said tubular wall of said central receptacle; annular contact means arranged to make electrical connection of the outer end face of said rotor wall with the inner end of the tubular wall of each outer receptacle; an inner curved conductor supported in said curved opening of said rotor wall, the outer end of said curved conductor being arranged to engage said contact head of said contact pin of each outer receptacle; means electrically connecting the inner end of said curved conductor with the inner end of the axial conductor of said central receptacle; means for rotating said rotor on said axis so as to move the outer end of said tubular wall from one to another of said outer receptacles; and cam means arranged to eiect separation of said annular contact means in a direction perpendicular to the plane defined by said end face so that said annular' contact means will pass across the exposed portion of said pin of each outer receptacle.

4. In a coaxial switch: a support having thereon a central receptacle and outer receptacles, each of said receptacles having a tubular wall forming an outer conductor and an axial conductor supported within said tubular wall, the inner conductor oteach of said outer receptacles comprising a tubular shell supported by insulator means, a contact pin axially movable in said shell and having a Contact head arranged to project from the inner end of said sleeve, cooperative shoulder means on said sleeve and said pin to limit the movement of said pin, and spring means acting between said pin and said sleeve; a rotor supported for rotation on the axis of said central receptacle, said rotor having a wall defining a curved opening leading from the inner end of said central receptacle to the inner end of each outer receptacle; contact means arranged to make electrical connection of the inner end of said rotor wall with the inner end of said tubular wall of said central receptacle; contact means arranged to make electrical connection of the outer end face of said rotor wall with the inner end of the tubular wall of each outer receptacle; an inner curved conductor supported in said curved opening of said rotor Wall, the outer end of said curved conductor being arranged to engage said contact head of said contact pin of each outer receptacle; means electrically connecting the inner end of said curved conductor with the inner end of the axial conductor of said central receptacle; means for rotating said rotor on said axis so as to move the outer end of said tubular wall from one to another of said outer receptacle; spring means arranged to force the outer end of said rotor tightly into engagement with the inner end of the tubular wall of each outer receptacle; and cam means arranged to bodily move said rotor so that its outer end will be spaced perpendicularly from the inner end of the tubular wall of each of said outer receptacles and pass across the exposed portion of said pin of each outer receptacle.

References Cited in the file of this patent UNITED STATES PATENTS 2,344,780 Kram et al. Mar. 21, 1944 2,435,978 Newkirk Feb. 17, 1948 2,473,565 Bird June 21, 1949 2,565,643 Baddour Aug. 28, 1951 

